perf: split router into per-field base vars; gather connection-static router data at connect

news/7068.breaking.md

@@ -0,0 +1 @@
+The root state gained five base vars holding the router data: `rx_router_session`, `rx_router_headers`, `rx_router_page`, `rx_router_url` and `rx_router_route_id`. A substate that declares one of these names now raises `BaseVarShadowsInheritedVarError`, the same error any other shadowed inherited var raises, and must rename its field. `State.router` itself is unchanged.

news/7068.deprecation.md

@@ -0,0 +1 @@
+Declaring a computed var dependency on the `router` var (`deps=["router"]`) is deprecated; depend on the router Var instead, e.g. `deps=[State.router.url]` for a single field or `deps=[State.router]` to keep tracking all of them.

news/7068.performance.md

@@ -0,0 +1,3 @@
+Store router data in separate base vars (session, headers, page, url, route_id) so a navigation delta only re-sends the fields that changed instead of the whole router, and gather the connection-scoped router data (headers, client IP, session id) once at connect time rather than on every event. `State.router` is unchanged for app code.
+
+The page URL is also persisted as the URL itself rather than as its parsed pieces: `ReflexURL` and `URLData` re-split on the way out of the state store instead of writing scheme, netloc, origin, path, query, query parameters and fragment alongside the href on every state write.

packages/reflex-base/news/7068.feature.md

@@ -0,0 +1 @@
+`VarData` now tracks every state field a var is built from in `field_dependencies`, a mapping of state name to that state's field names, unioned and deduped as vars merge. A computed var depending on a composite var (`deps=[SomeState.composite]`) is now invalidated when any of its underlying fields changes — including fields belonging to a different state, which previously went untracked. `state` and `field_name` still report the first state and its first field, so existing readers are unaffected; read `field_dependencies` when you need every state a var reaches.

packages/reflex-base/news/7068.performance.md

@@ -0,0 +1 @@
+The event processor now refreshes only the router vars whose backing `router_data` keys actually changed, so a navigation no longer rebuilds and re-sends the connection-scoped session and header data. `ROUTER_VARS` names the per-field router vars that replaced the single `router` var on the root state.

packages/reflex-base/src/reflex_base/constants/__init__.py

@@ -60,6 +60,12 @@
     ROUTER,
     ROUTER_DATA,
     ROUTER_DATA_INCLUDE,
+    ROUTER_HEADERS,
+    ROUTER_PAGE,
+    ROUTER_ROUTE_ID,
+    ROUTER_SESSION,
+    ROUTER_URL,
+    ROUTER_VARS,
     DefaultPage,
     Page404,
     RouteArgType,
@@ -86,6 +92,12 @@
     "ROUTER",
     "ROUTER_DATA",
     "ROUTER_DATA_INCLUDE",
+    "ROUTER_HEADERS",
+    "ROUTER_PAGE",
+    "ROUTER_ROUTE_ID",
+    "ROUTER_SESSION",
+    "ROUTER_URL",
+    "ROUTER_VARS",
     "ROUTE_NOT_FOUND",
     "SESSION_STORAGE",
     "SETTER_PREFIX",

packages/reflex-base/src/reflex_base/constants/route.py

@@ -11,10 +11,30 @@ class RouteArgType(SimpleNamespace):
     LIST = "arg_list"
 
 
-# the name of the backend var containing path and client information
+# the name of the state attribute exposing path and client information
 ROUTER = "router"
 ROUTER_DATA = "router_data"
 
+# The names of the per-field base vars holding router data on the root state.
+# Session and headers are constant for the lifetime of a websocket connection,
+# while page, url, and route_id change on every navigation; keeping them in
+# separate vars means a navigation delta only re-sends the navigation fields.
+# The `rx_` prefix keeps them from colliding with a field an app already
+# defines; `router` itself stays unprefixed as the public switchboard.
+ROUTER_SESSION = "rx_router_session"
+ROUTER_HEADERS = "rx_router_headers"
+ROUTER_PAGE = "rx_router_page"
+ROUTER_URL = "rx_router_url"
+ROUTER_ROUTE_ID = "rx_router_route_id"
+
+ROUTER_VARS = (
+    ROUTER_SESSION,
+    ROUTER_HEADERS,
+    ROUTER_PAGE,
+    ROUTER_URL,
+    ROUTER_ROUTE_ID,
+)
+
 
 class RouteVar(SimpleNamespace):
     """Names of variables used in the router_data dict stored in State."""

packages/reflex-base/src/reflex_base/event/processor/base_state_processor.py

@@ -13,7 +13,6 @@
 from time import perf_counter
 from typing import TYPE_CHECKING, Any
 
-from reflex.istate.data import RouterData
 from reflex.istate.manager.token import BaseStateToken
 from reflex.istate.proxy import StateProxy
 from reflex.utils import types
@@ -431,12 +430,20 @@ async def _execute_event(
             )
 
             # re-assign only when the value is set and different
-            if router_data and state.router_data != router_data:
-                # assignment will recurse into substates and force recalculation of
-                # dependent ComputedVar (dynamic route variables)
-                state.router_data = router_data
-                if state.router != (router := RouterData.from_router_data(router_data)):
-                    state.router = router
+            if (
+                router_data
+                and (previous_router_data := state.router_data) != router_data
+            ):
+                # only the router vars whose backing keys changed are rebuilt
+                # and re-sent; session/headers stay put across navigations.
+                merged_router_data = state._update_router_vars(
+                    router_data, previous_router_data
+                )
+                # Store what it merged, not the payload, so a partial payload
+                # does not drop the keys it omits. Only on a real change: the
+                # assignment dirties router_data and marks the state touched.
+                if merged_router_data != previous_router_data:
+                    state.router_data = merged_router_data
 
             # Preprocess the event.
             if (